1. Field of the Invention
This invention pertains to disc brakes or the like for motor shafts, equipment shafts or other similar rotating members, and more particularly relates to a brake (or clutches) which may easily be adjusted to maintain a desired braking force when engaged and which maintains a constant clearance between the brake pads and the disc when the brake is released.
2. Description of Prior Art
Hydraulically released, spring set brakes are well known in the art as indicated by U.S. Pat. No. 3,456,767 which issued to Hollnagel et al. on July 22, 1969. Although this patent discloses a disc brake which is hydraulically released, it does not disclose any means for maintaining a constant clearance or gap between the brake pads and the disc when the brake is hydraulically released but instead allows the clearance gap to increase as the pads wear.
U.S. Pat. No. 3,633,715 which issued to Burnett on Jan. 11, 1972 discloses a disc brake actuator which utilizes a deformable annular seal between a piston and cylinder to assure that the friction pads retract a sufficient distance from the rotor disc despite wear of the friction material. In addition to the deformable annular seal, the patentee discloses a nut which is rotated on a threaded member in response to an abnormally long stroke of the piston thereby correcting the stroke of the piston to provide the desired gap when released.
The United States patents to Airheart et al. U.S. Pat. No. 3,113,646 which issued on Dec. 10, 1963; and Dotto U.S. Pat. No. 3,064,765 which issued on Nov. 20, 1962 each disclose another type of device for assuring a desired gap between the disc brake rotor and the friction pads when the brake is released. In both of these patents when the gap becomes excessive due to wear of the friction pads, sufficient hydraulic force is applied to overcome the frictional grip between a shaft and a friction washer or the like thereby repositioning the shaft relative to the washer and support housing thereby re-establishing the desired gap.